The present invention relates to a slat track device for an aircraft wing, as well as to an aircraft wing comprising such a slat track device. Such an aircraft wing comprises a main wing and a slat, wherein the slat is movably connected to the main wing via the slat track device.
The slat track device comprises a beam-shaped main load bearing track structure, a guidance surface, a connection device and an engagement device.
The track structure is formed as an elongate support member which extends not necessarily strait but rather bent in the shape of a curved path along which the slat is moved with respect to the main wing when the slat is extended or retracted. The cross section of the track structure can have different shapes, such as a H-shape, which is commonly used in the Prior Art. The track structure is configured to be connected, such as fixedly connected, to a slat, such as at the first end of the track structure. The track structure is further configured to be movably connected to a main wing, such as for example that a translatory movement of the track structure along its longitudinal direction relative to the main wing is permitted.
The guidance surface is provided at the track structure, such as fixedly connected to or integrally formed with the track structure, and has an elongate shape extending along the longitudinal direction of the track structure.
The guidance surface is configured for being guided along a corresponding guidance device provided at a main wing. Such a guidance device may include rollers or slight surfaces, forming a guidance path. The guidance surface may include several surface portions provided on opposite sides of the track structure, so that movement of the track structure with respect to the corresponding guidance device is allowed only along the guidance path along the longitudinal direction of the track structure.
The connection device is provided at the track structure, such as a fixedly connected to or integrally formed with the track structure, such as at the first end of the track structure. The connection device is configured for connecting the track structure to a slat, such as in a fixed manner, e.g. with two hinges, one master and one slave.
The engagement device is provided at the track structure, such as connected to or integrally formed with the track structure. The engagement device is configured for engagement with a drive member of a drive unit provided at a main wing for moving the slat.
Such slat track devices are commonly known in the art and used in several aircraft models. Until recently, the fail-safe requirements of the aeronautical authorities, specifically of the US authority FAA (Federal Aviation Administration), specified that it had to be proven that a crack existing in the track structure of such a slat track device detected for the first time in a first routine check, does not propagate through the entire track structure until the next routine check. This means, it needs to be proven that the crack propagation through the entire track structure takes at least the time of an interval between two routine checks. In such a way it is guaranteed that a crack propagating in the track structure is detected at least in one routine check.
However, the FAA recently modified or clarified these fail-safe requirements for the slat track device. The track structure is now required to include two separate main load paths, wherein when one main load path fails, the other main load path is required to still be capable of maintaining the connection between the slat and the main wing during flight.